The present disclosure relates generally to an insulation assembly for use with cryogenic propellant vessels, and, more specifically, to an insulation assembly that includes a micro-truss reinforced cryofoam.
Aerospace vehicle designs commonly utilize a variety of propellants to supply both launch/takeoff and maneuvering power requirements. The quantity of propellant required for most missions, especially for launch/takeoff requirements, often generates severe design constraints and can require considerable portions of vehicle size to be dedicated towards the carrying of propellant. The use of cryogenic propellants allows the propellants to be maintained in a liquid state rather than in their room temperature gaseous form. This allows a greater quantity of propellant to be stored in a smaller container. This, in turn, improves the design capabilities of aerospace vehicles.
Current cryogenic propellant vessel technology for expendable launch systems such as the external vessel of the space shuttle use spray-on foam insulation. This technology, however, does not commonly satisfy the strength and reusability requirements associated with multi-mission flight environments. Expendable launch systems are often not considered appropriate for integration into reusable vehicle designs, such as commercial aircraft and reusable space vehicles. For example, reusable space vehicle designs often require such vehicles to carry the cryogenic propellant vessels through launch, on-orbit, and reentry. The cryogenic insulation (“cryoinsulation”) is required to reduce launch pad cryogen boil-off and thermally protect propellant vessels during ground servicing, launch, on-orbit, and reentry. In addition, the cryoinsulation must be robust enough to withstand repeated thermal cycling.
At least some known cryoinsulation is applied to the exterior of the propellant vessels and can consist of a foam insulation layer. However, such foams are generally not suitable as cryoinsulation by themselves owing to their tendency to crack, delaminate from the propellant vessel walls, and/or fragment (a condition often referred to as spalling where flakes of a material detach from a larger solid body) when subjected to a combination of cryogenic temperatures and mechanical loads. Therefore, at least some known cryoinsulation includes and a honeycomb core that provides mechanical reinforcement to the foam layer to reduce cracking, delamination, and spalling. However, such honeycomb material substantially increases the weight of the reusable aerospace vehicle, which leads to additional propellant consumption and higher costs.
Accordingly, the present disclosure provides for a cryofoam insulation that satisfies the strength and reusability requirements associated with multi-mission flight environments. Furthermore, the present disclosure provides for a cryofoam insulation that is lightweight, and thus reduces the operating costs of the vehicle.